| Message ID | 20220921014103.587954-1-npiggin@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [1/2] powerpc/64s: Fix GENERIC_CPU build flags for PPC970 / G5 | expand |
Le 21/09/2022 à 03:41, Nicholas Piggin a écrit : > Big-endian GENERIC_CPU supports 970, but builds with -mcpu=power5. > POWER5 is ISA v2.02 whereas 970 is v2.01 plus Altivec. 2.02 added > the popcntb instruction which a compiler might use. > > Use -mcpu=power4. > > Fixes: 471d7ff8b51b ("powerpc/64s: Remove POWER4 support") > Signed-off-by: Nicholas Piggin <npiggin@gmail.com> > --- > arch/powerpc/Makefile | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile > index 02742facf895..140a5e6471fe 100644 > --- a/arch/powerpc/Makefile > +++ b/arch/powerpc/Makefile > @@ -152,7 +152,7 @@ CFLAGS-$(CONFIG_GENERIC_CPU) += -mcpu=power8 > CFLAGS-$(CONFIG_GENERIC_CPU) += $(call cc-option,-mtune=power9,-mtune=power8) > else > CFLAGS-$(CONFIG_GENERIC_CPU) += $(call cc-option,-mtune=power7,$(call cc-option,-mtune=power5)) > -CFLAGS-$(CONFIG_GENERIC_CPU) += $(call cc-option,-mcpu=power5,-mcpu=power4) > +CFLAGS-$(CONFIG_GENERIC_CPU) += -mcpu=power4 > endif > else ifdef CONFIG_PPC_BOOK3E_64 > CFLAGS-$(CONFIG_GENERIC_CPU) += -mcpu=powerpc64 That else ifdef CONFIG_PPC_BOOK3E_64 looks odd. I might have forgotten to drop something. Since commit d6b551b8f90c ("powerpc/64e: Fix build failure with GCC 12 (unrecognized opcode: `wrteei')") it is not possible anymore to select CONFIG_GENERIC_CPU if not book3s64. Christophe
On Wed, Sep 21, 2022 at 11:41:02AM +1000, Nicholas Piggin wrote: > Big-endian GENERIC_CPU supports 970, but builds with -mcpu=power5. > POWER5 is ISA v2.02 whereas 970 is v2.01 plus Altivec. 2.02 added > the popcntb instruction which a compiler might use. > > Use -mcpu=power4. > > Fixes: 471d7ff8b51b ("powerpc/64s: Remove POWER4 support") > Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org> Thank you! Maybe superfluous, but some more context: GCC's -mcpu=power4 means POWER4+, ISA 2.01, according to our documentation. There is no difference with ISA 2.00 (what plain POWER4 implements) for anything GCC does. Segher
On Thu Sep 22, 2022 at 4:50 AM AEST, Segher Boessenkool wrote: > On Wed, Sep 21, 2022 at 11:41:02AM +1000, Nicholas Piggin wrote: > > Big-endian GENERIC_CPU supports 970, but builds with -mcpu=power5. > > POWER5 is ISA v2.02 whereas 970 is v2.01 plus Altivec. 2.02 added > > the popcntb instruction which a compiler might use. > > > > Use -mcpu=power4. > > > > Fixes: 471d7ff8b51b ("powerpc/64s: Remove POWER4 support") > > Signed-off-by: Nicholas Piggin <npiggin@gmail.com> > > Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org> > > Thank you! > > Maybe superfluous, but some more context: GCC's -mcpu=power4 means > POWER4+, ISA 2.01, according to our documentation. There is no > difference with ISA 2.00 (what plain POWER4 implements) for anything > GCC does. Huh, okay. Well I guess we are past that point now, interesting that another ISA version was done for 4+ though, and then another for 5. I don't see a list of changes from 2.00 in the public version, I wonder what else changed other than mtmsrd. Thanks, Nick
On Fri, Sep 23, 2022 at 05:17:45PM +1000, Nicholas Piggin wrote: > On Thu Sep 22, 2022 at 4:50 AM AEST, Segher Boessenkool wrote: > > On Wed, Sep 21, 2022 at 11:41:02AM +1000, Nicholas Piggin wrote: > > > Big-endian GENERIC_CPU supports 970, but builds with -mcpu=power5. > > > POWER5 is ISA v2.02 whereas 970 is v2.01 plus Altivec. 2.02 added > > > the popcntb instruction which a compiler might use. > > > > > > Use -mcpu=power4. > > > > > > Fixes: 471d7ff8b51b ("powerpc/64s: Remove POWER4 support") > > > Signed-off-by: Nicholas Piggin <npiggin@gmail.com> > > > > Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org> > > > > Thank you! > > > > Maybe superfluous, but some more context: GCC's -mcpu=power4 means > > POWER4+, ISA 2.01, according to our documentation. There is no > > difference with ISA 2.00 (what plain POWER4 implements) for anything > > GCC does. > > Huh, okay. Well I guess we are past that point now, interesting that > another ISA version was done for 4+ though, and then another for 5. > I don't see a list of changes from 2.00 in the public version, I > wonder what else changed other than mtmsrd. I think searching for "POWER4+" will give you everything. I cannot find a public 2.00 either, yeah. I listed everything I think changed elsewhere in the thread. Segher
On Wed, 21 Sep 2022 11:41:02 +1000, Nicholas Piggin wrote: > Big-endian GENERIC_CPU supports 970, but builds with -mcpu=power5. > POWER5 is ISA v2.02 whereas 970 is v2.01 plus Altivec. 2.02 added > the popcntb instruction which a compiler might use. > > Use -mcpu=power4. > > > [...] Applied to powerpc/next. [1/2] powerpc/64s: Fix GENERIC_CPU build flags for PPC970 / G5 https://git.kernel.org/powerpc/c/58ec7f06b74e0d6e76c4110afce367c8b5f0837d [2/2] powerpc/64s: update cpu selection options https://git.kernel.org/powerpc/c/7fd123e544886bf04fa853869efe55cb3f22d0c0 cheers
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile index 02742facf895..140a5e6471fe 100644 --- a/arch/powerpc/Makefile +++ b/arch/powerpc/Makefile @@ -152,7 +152,7 @@ CFLAGS-$(CONFIG_GENERIC_CPU) += -mcpu=power8 CFLAGS-$(CONFIG_GENERIC_CPU) += $(call cc-option,-mtune=power9,-mtune=power8) else CFLAGS-$(CONFIG_GENERIC_CPU) += $(call cc-option,-mtune=power7,$(call cc-option,-mtune=power5)) -CFLAGS-$(CONFIG_GENERIC_CPU) += $(call cc-option,-mcpu=power5,-mcpu=power4) +CFLAGS-$(CONFIG_GENERIC_CPU) += -mcpu=power4 endif else ifdef CONFIG_PPC_BOOK3E_64 CFLAGS-$(CONFIG_GENERIC_CPU) += -mcpu=powerpc64
Big-endian GENERIC_CPU supports 970, but builds with -mcpu=power5. POWER5 is ISA v2.02 whereas 970 is v2.01 plus Altivec. 2.02 added the popcntb instruction which a compiler might use. Use -mcpu=power4. Fixes: 471d7ff8b51b ("powerpc/64s: Remove POWER4 support") Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- arch/powerpc/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)